This invention relates in general to flowing media proportioning devices and in particular to a new and useful mixing and proportioning device particularly for use in controlling flowing media in respirators.
The invention concerns a mixing and proportioning device for flowing media, particularly produced from gaseous components, which has feeding lines, each with a pressure reducer, that lead into a mixing chamber of the device and flow out through a mixed gas discharge pipe. The device includes one wall of the mixing chamber which is formed by a pressure-sensitive spring-mounted device that is provided for the discontinuous closing off of the feeding lines from the mixed gas discharge pipe since a constant pressure regulator is also provided.
A mixing and proportioning device of a similar type has become known from the DE-S No. 22 24 588. In this device two gas components to be mixed are introduced into a mixing chamber through one feeding line, respectively. Each feeding line is equipped with a valve for its complete opening or closing. The valve heads are connected to a pressure-sensitive device that interrupts or releases discontinuously the gas supply to the mixing chamber in dependence on the excess pressure in the mixing chamber. The mixing chamber is connected to a mixed gas discharge pipe, through which the mixed gas is supplied to the user. When the pressure in the mixing chamber drops below a given value due to increased removal of mixed gas, the inlet valves are opened to allow gas with a higher pressure to enter the mixing chamber. When the removal of mixed gas from the mixed gas discharge pipe drops, thus causing a rise of the pressure in the mixing chamber, the pressure-sensitive device interrupts the gas supply into the mixing chamber by closing the inlet valves discontinuously. The switching pressure for the opening and closing of the inlet valves is determined by the excess pressure in the mixing chamber, in relation to the ambient pressure.
The pressure-sensitive device, which closes the feeding lines when the pressure in the mixing chamber drops below a given value, is provided since the adjusted mixing ratios cannot be maintained as the component pressure drops below a certain value, or as the removal rate of flow from the mixed gas line drops below a certain value.
But since the pressure value for the discontinuous opening and closing of the feeding lines is adjusted at a fixed setting with respect to the ambient pressure, the user will receive only the standard low mixed gas pressure, even when a higher operating pressure in the feeding lines is available. A utilization of higher available feeding pressures for the creation of higher mixed gas pressure is impossible.